Method for making collector arrangement for magnetotransistor

ABSTRACT

A collector arrangement for a magnetotransistor (10, 25, 30) and a method for making the magnetotransistor (10, 25, 30). A portion of a semiconductor substrate (11) is doped to form a base region (13). The base region is doped to form an emitter region (16, 26, 36) and a collector region (17, 27, 37) such that the collector region (17, 27, 37) surrounds and is spaced apart from the emitter region (16, 26, 36). Collector contacts (C 1  -C 8  and C 5  &#39;-C 8  &#39;, C 13  -C 16 ) are symmetrically formed in the collector region (17, 27, 37). In a three-dimensional magnetotransistor (10, 25) the collector contacts include split-collector contacts (C 5  -C 8  and C 5  &#39;-C 8  &#39;).

This is a division of application Ser. No. 08/069,802, filed Jun. 1,1993, now U.S. Pat. No. 5,323,050.

BACKGROUND OF THE INVENTION

The present invention relates, in general, to magnetotransistors, andmore particularly, to a collector arrangement for magnetotransistors.

Magnetotransistors are magnetic field sensors that are commonly used todetect the presence and orientation of a magnetic field or moreparticularly a magnetic flux density. Typically, these sensors aresemiconductor devices that include an injection region, a conductionregion, and a collection region. Charge carriers, i.e., electrons orholes, are injected from the injection region into the conduction regionand are subsequently collected in the collection region. An example ofsuch a sensor is a lateral magnetotransistor having an emitter region, abase region, and a collector region, wherein the emitter region servesas the injection region, the base region serves as the conductionregion, and the collector region serves as the collection region.

When a magnetic field is applied to the magnetotransistor, it exerts anelectromagnetic force on the charge carriers. This force, commonlyreferred to as a Lorentz force, deflects the charge carriers travelingthrough the base region thereby creating an imbalance in the number ofcharge carriers collected by the collector region. In other words, thecollector currents become imbalanced. This imbalance may be exploited todetermine the strength and orientation of the magnetic flux density.

Two important types of magnetotransistors are two-dimensional (2D)magnetotransistors which detect the x and y directional components,B_(x) and B_(y), respectively, of the magnetic flux density andthree-dimensional (3D) magnetotransistors which detect the x, y, and zdirectional components of the magnetic flux density, B_(x), B_(y), andB_(z), respectively. A drawback of 2D and 3D magnetotransistors is thatthe noise signals associated with the currents in each collector areuncorrelated and may mask the imbalance in the collector currentattributed to the magnetic flux density. Moreover, in 3Dmagnetotransistors there is a cross-sensitivity between the chargecarrier flow in the y-direction and the B_(x) component of the magneticflux density, and between the charge carrier flow in the x-direction andB_(y) component of the magnetic flux density.

Accordingly, it would be advantageous to have a magnetotransistor and amethod for making the magnetotransistor that reduces the noise due tothe uncorrelated collector currents. It would be of further advantagethat the 3D magnetotransistor and the method for making the 3Dmagnetotransistor eliminate cross-sensitivity between the charge carrierflow in the y-direction and the B_(x) component and between the chargecarrier flow in the x-direction and the B_(y) component.

SUMMARY OF THE INVENTION

Briefly stated, the present invention is a collector arrangement for amagnetotransistor and a method for making said magnetotransistor. In oneaspect of the present invention a magnetotransistor comprises asemiconductor substrate of a first conductivity type which has aprincipal surface. A base region of a second conductivity type extendsfrom the principal surface into the semiconductor substrate. An emitterregion of the first conductivity type extends from the principal surfaceinto the base region. An annularly shaped collector region of the firstconductivity type laterally surrounds and is spaced apart from theemitter region, wherein the collector region extends from the principalsurface into the base region. A base contact is formed on the principalsurface of the base region, an emitter contact is formed on theprincipal surface of the emitter region, and a plurality of collectorcontacts are formed on the principal surface in the collector region,wherein a first and a second of the plurality of collector contacts areadjacent opposite sides of the emitter region, and a third and a fourthof the plurality of collector contacts are adjacent opposite sides ofthe emitter region. The sides adjacent the first and second collectorcontacts being different than the sides adjacent the third and fourthcollector contacts.

Another aspect of the present invention is a method of forming themagnetotransistor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a highly-enlarged plan view of one embodiment of aportion of a three-dimensional magnetic field sensor in accordance withthe present invention;

FIG. 2 illustrates a cross-sectional perspective view of the magneticfield sensor of FIG. 1;

FIG. 3 is an equivalent circuit of the magnetic field sensor of FIG. 1;

FIG. 4 illustrates a highly-enlarged plan view of a second embodiment ofa portion of a three-dimensional magnetic field sensor in accordancewith the present invention; and

FIG. 5 illustrates a plan view of an embodiment of a two-dimensionalmagnetic field sensor in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a highly-enlarged plan view of a first embodiment ofa magnetic field sensor 10, whereas FIG. 2 illustrates a cross-sectionalperspective view of magnetic field sensor 10 taken along section lines2-2 of FIG. 1. For clarity, conductive traces 31 and 32 of FIG. 1 havebeen omitted from FIG. 2. Preferably, magnetic field sensor 10 is alateral magnetotransistor comprising a lateral NPN transistor. Althoughthe present invention is described in terms of an NPN transistor, itshall be understood that magnetic field sensor 10 may comprise a lateralPNP transistor. As those skilled in the art will recognize, the dopanttypes for a magnetic field sensor comprising a lateral PNP transistorwill be opposite those described hereinafter. Further, the notation "N⁻" refers to N type dopant or impurity material concentrations less thanabout 10¹⁵ atoms/cm³, the notation "N⁺ " refers to N type dopantconcentrations greater than about 10¹⁸ atoms/cm³. Likewise, the notation"P⁻ " refers to P type dopant or impurity material concentrations lessthan about 10¹⁵ atoms/cm³ , the notation "P⁺ " refers to P type dopantconcentrations greater than about 10¹⁸ atoms/cm³.

Magnetotransistor 10 comprises a semiconductor substrate 11 which isdoped with an N type dopant and has a principal or major surface 12.Preferably, semiconductor substrate 11 is silicon having a <100> crystalorientation and doped with phosphorus in a concentration of 10¹⁵atoms/cm³. Other suitable N type dopants include arsenic and antimony. Abase region 13 is formed in a portion of semiconductor substrate 11 bydoping semiconductor substrate 11 with a P type dopant. By way ofexample, base region 13 extends from principal surface 12 approximately4 micrometers (μm) into semiconductor substrate 11. Preferably, the Ptype dopant is boron having a concentration of 10¹⁶ atoms/cm³.

An emitter region 16 is formed within base region 13 by doping a firstportion of base region 13 with an N type dopant such as phosphorus. In afirst embodiment, emitter region 16 is an annular shaped octagonalstructure having eight sides and eight corners. Emitter region 16 is anN⁺ region having, for example, a dopant concentration of 10²⁰ atoms/cm³.In addition, a collector region 17 is formed within base region 13 bydoping a second portion of base region 13 with the N type dopant havinga concentration of 10²⁰ atoms/cm³. Collector region 17 is an annularlyshaped N⁺ region that conforms to the shape of emitter region 16, andlaterally surrounds and is spaced apart from emitter region 16. For abase region 13 having a junction depth of 4 μm, emitter and collectorregions 16 and 17, respectively, extend from principal surface 12approximately 1 μm into base region 13. In addition, an optionalsubstrate contact region 18 of N⁺ type dopant is formed in a portion ofsemiconductor substrate 11 adjacent to base region 13. Preferably,emitter region 16, collector region 17, and substrate contact region 18are formed simultaneously.

An optional base contact region 20 is formed by doping a portion of baseregion 13 with a P⁺ type dopant. Base contact region 20 is an annularlyshaped region that conforms to the shape of collector region 17 suchthat it laterally surrounds and is spaced apart from collector region17. Preferably, a plurality of injection suppression regions 21 areformed that extend laterally from the portion of base region 13 that isbetween emitter region 16 and collector region 17, through the cornersof emitter region 16, and into emitter region 16. Preferably, basecontact region 20 and injection suppression regions 21 are formed in thesame doping step. More particularly, eight injection suppression regions21 are formed through each corner of emitter region 16. Injectionsuppression regions 21 are formed by doping the portions of base region13 and emitter region 16 with a P⁺ type dopant. Preferably, theconcentration of the P⁺ type dopant forming injection suppressionregions 21 is approximately 10²⁰ atoms/cm³. Although it is preferablethat injection suppression regions 21 and base contact regions 20 beformed simultaneously, they may be formed sequentially wherein injectionsuppression regions 21 are formed either before or after base contactregion 20.

Injection suppression regions 21 form eight charge carrier channelsindicated by arrows 22 extending from emitter region 16 into base region13. Each injection suppression region 21 is shaped such that the chargecarrier channels indicated by arrows 22 have parallel sides 23. Sides 23are formed from a PN junction and have a built-in potential sufficientto direct charge carrier movement parallel to sides 23. Injectionsuppression regions 21 extend into base region 13 to further govern thedirection of charge carrier movement. When the PN junction formedbetween emitter region 16 and base region 13 is forward biased, chargecarriers, i.e., electrons for an NPN magnetotransistor, are injectedthrough the charge carrier channels indicated by arrows 22 and arecollected by collector region 17. Thus, a large built-in potential, inconjunction with the difference in dopant concentrations between baseregion 13 and injection suppression regions 21, serves to suppresscarrier injection through the corners of emitter region 16 and to directthe carrier flow through the charge carrier channels indicated by arrows22. Methods of doping semiconductor substrate 11 to form base region 13,emitter region 16, collector region 17, base contact region 20, andinjection suppression regions 21 are well known to those skilled in theart.

FIG. 1 further illustrates a contact and a metallization scheme designedto provide a three-dimensional (3D) magnetotransistor, i.e., amagnetotransistor capable of detecting x-directional (B_(x)),y-directional (B_(y)), and z-directional (B_(z)) components of amagnetic flux density (B). Magnetotransistor 10 has a set of fourcollector contacts, labeled C₁, C₂, C₃, and C₄ in FIG. 1, whereincollector contacts C₁ and C₃ detect B_(x) and collector contacts C₂ andC₄ detect B_(y). Collector contacts C₁ and C₃ are formed on principalsurface 12 of collector region 17 such that they are across from eachother on opposite sides of emitter region 16. Moreover, collectorcontacts C₂ and C₄ are formed on principal surface 12 of collectorregion 17 such that they are across from each other on opposite sides ofemitter region 16. Collector contacts C₁ and C₃ are adjacent oppositesides of emitter region 16 and collector contacts C₂ and C₄ are adjacentopposite sides of collector region 16, wherein the sides adjacentcollector contacts C₁ and C₃ are different than the sides adjacentcollector contacts C₂ and C₄. In other words, collector contact C₁ ispositioned 90 degrees from collector contacts C₂ and C₄, and 180 degreesfrom collector contact C₃.

Further, magnetotransistor 10 has four pairs of split-collector contactsC₅, C₅ ', C₆, C₆ ', C₇, C₇ ', C₈, and C₈ ' for detecting B_(z). Eachpair of split-collector contacts comprises two collector contacts whichare formed adjacent one another on principal surface 12 of collectorregion 17. A first pair of split-collector contacts, comprising C₅ andC₅ ', and a second pair of split-collector contacts, comprising C₇ andC₇ ', are formed on principal surface 12 of collector region 17 suchthat they are across from each other on opposite sides of emitter region16. A third pair of split-collector contacts, comprising C₆ and C₆ ',and a fourth pair of split-collector contacts, comprising C₈ and C₈ ',are formed on principal surface 12 of collector region 17 such that thethird and fourth pairs of split-collector contacts are across from eachother on opposite sides of emitter region 16. The first pair ofsplit-collector contacts, C₅ and C₅ ' is between collector contacts C₁and C₄, the second pair, C₇ and C₇ ', is between collector contacts C₂and C₃, the third pair, C₆ and C₆ ', is between collector contacts C₃and C₄, and the fourth pair, C₈ and C₈ ', is between collector contactsC₁ and C₂. In other words, the first pair, C₅ and C₅ ', is positioned180 degrees from the second pair, C₇ and C₇ ', and the third pair, C₆and C₆ ', is positioned 180 degrees from the fourth pair, C₈ and C₈ ',such that the first pair, C₅, C₅ ' is bilaterally symmetric with thesecond pair, C₇, C₇ ', and the third pair, C₆, C₆ ', is bilaterallysymmetric with the fourth pair, C₈, C₈ '. As illustrated in FIG. 1,split collector contacts C₅, C₆, C₇, and C₈ are connected with aconductive material 31 and serve as a single collector contact C_(z) andsplit collector contacts C₅ ', C₆ ', C₇ ', and C₈ ' are connected with aconductive material 32 and serve as a single collector contact C_(z) '.In other words, split-collector contacts C₅, C₆, C₇, and C₈ areelectrically coupled with a conductive trace 31 and split-collectorcontacts C₅ ', C₆ ', C₇ ', and C₈ ' are electrically coupled with aconductive trace 32. Portions of split-collector contacts C₅ -C₈ and C₅'-C₈ ' which are below conductive traces 31 and 32 are shown as dashedlines.

Magnetotransistor 10 of FIGS. 1 and 2 is schematically illustrated inFIG. 3. An example of a bias arrangement for magnetotransistor 10 isshown wherein a constant base current I_(B) is supplied tomagnetotransistor 10 via base region 13. Each collector contact iscoupled to a collector voltage V_(C) and the substrate contact region 18is connected to a substrate voltage V_(S). As those skilled in the artare aware, the values of the base current I_(B), the collector voltageV_(C), and the substrate voltage V_(S) determine the operating point inthe forward active mode of operation. By way of example, I_(B) is 1milliampere (mA), V_(C) is 5 volts, and V_(S) is 5 volts.

In the forward active mode of operation, electrons are injected fromemitter region 16 into base region 13 and collected by collector region17. In the absence of a magnetic field, the electrons collected bycollector region 17 are evenly distributed among the collector contactsbecause of the symmetry of magnetotransistor 10. When a magnetic fieldhaving a magnetic flux density B is applied to magnetotransistor 10, theB_(x), B_(y), and B_(z) components of the magnetic flux density createan imbalance in the number of electrons collected by the collectorcontacts due to the action of the Lorentz force.

More particularly, B_(z), which is perpendicular to principal surface 12(FIG. 2), causes a deflection of electrons towards split-collectorcontacts C₅, C₆, C₇, and C₈ (collectively referred to as C_(z) in FIG.3), whereas the same component causes a deflection of electrons awayfrom collector contacts C₅ ', C₆ ', C₇ ', and C₈ ' (collectivelyreferred to as C_(z) ' in FIG. 3). Thus, more electrons are collected inthe vicinity of split-collector contacts C₅, C₆, C₇, and C₈ than in thevicinity of split-collector contacts C₅ ', C₆ ', C₇ ', and C₈ '.Accordingly, collector current I_(CZ) is greater than collector currentI_(CZ) '. Thus, the difference between the collector currents I_(CZ) andI_(CZ) ' is used to detect B_(z). As those skilled in the art willrecognize, collector current I_(CZ) is the sum of the currents flowingthrough split-collector contacts, C₅, C₆ , C₇, and C₈, whereas collectorcurrent I_(CZ) ' is the sum of the currents flowing throughsplit-collector contacts C₅ ', C₆ ', C₇ ', and C₈ '.

The B_(x) component, which is parallel to principal surface 12 andoriented in the x-direction, causes a deflection of electrons flowing inthe y-direction i.e., electrons flowing towards collector contacts C₁and C₃ of FIG. 1. Thus, B_(x) causes a deflection of electrons towardscollector contact C₁ and away from collector contact C₃. Accordingly,the collector current shown in FIG. 3 as I_(C1) is greater than thecollector current I_(C3) in the presence of B_(y). Although B_(y) isalso parallel to principal surface 12, it is oriented in they-direction. Thus, B_(y) causes a deflection of electrons flowing in thex-direction, i.e., electrons flowing towards collector contacts C₂ andC₄, such that the collector current I_(C4) is greater than collectorcurrent I_(C2). In other words, the charge carriers collected bycollector contacts C₁ and C₃ are differentially deflected by the B_(x)component of the magnetic flux density, whereas the charge carrierscollected by collector contacts C₂ and C₄ are differentially deflectedby the B_(y) component of the magnetic flux density. Thus, the B_(x)component deflects the charge carriers away from collector contact C₁and towards collector contact C₃, whereas the B_(y) component deflectsthe charge carriers away from collector contact C₂ and towards collectorcontact C₄. Therefore, the difference in collector currents I_(C1) andI_(C3) may be used to detect B_(x), whereas the difference in collectorcurrents I_(C4) and I_(C2) may be used to detect B_(y).

In addition, there are x-directional velocity vector components, V_(x),and y-directional velocity vector components, V_(y), which result fromthe "off-axis" positioning of the split-collectors. These velocityvector components, in conjunction with B_(x) and B_(y), introduce across sensitivity in the flow of electrons from emitter region 16 to thesplit-collector contacts. More particularly, B_(x) lowers the number ofelectrons collected by split-collector contacts C₅ and C₅ ' as well asby split collector contacts C₆ and C₆ ' while increasing the number ofelectrons collected by split-collector contacts C₇ and C₇ ' and bysplit-collector contacts C₈ and C₈ '. Since split-collector contacts C₅,C₆, C₇, and C₈ are connected, there is no net change in collectorcurrent I_(CZ) due to B_(x). Similarly, since split-collector contactsC₅ ', C₆ ', C₇ ', and C₈ ' are coupled together, there is no net changein collector current I_(C3) ' due to B_(x). In like fashion, there is nonet change in collector current I_(CZ) and I_(CZ) ' due to B_(y).

FIG. 4 illustrates a highly-enlarged plan view of a second embodiment ofa magnetic field sensor 25. Reference numerals for FIG. 4 correspondingto like elements of FIG. 1 have been retained. For clarity, conductivetraces 31 and 32 have been omitted from FIG. 4. Although both FIGS. 1and 4 have emitter, collector, and base contact regions, differentreference numerals have been attached to these elements since they havedifferent shapes in FIGS. 1 and 4. In the second embodiment, emitterregion 26 is a circular N⁺ region having a dopant concentration of, forexample, 10²⁰ atoms/cm³. Collector region 27 is a circular shaped N⁺region that conforms to the shape of emitter region 26, and laterallysurrounds and is spaced apart from emitter region 26. Collector region27 is formed within base region 13 by doping a second portion of baseregion 13 with the N type dopant having a concentration of 10²⁰atoms/cm³. A base contact region 29 is formed by doping a portion ofbase region 13 with a P⁺ type dopant. Base contact region 29 is circularin shape, conforming to the shape of collector region 27, and laterallysurrounds and is spaced apart from collector region 27.

Although, the embodiments shown in FIGS. 1 and 4 illustrate four sets ofsplit-collector contacts, it shall be understood that the presentinvention may be implemented using two sets of split-collector contacts,wherein the two sets of split-collector contacts are on opposite sidesof emitter regions 16 or 26. When using only two sets of split-collectorcontacts, it may be desirable to form the emitter suppression regions onthe sides without the split-collector contacts such that the emittersuppression regions extend along the entire side of the emitter regionswithout the split-collector contacts. By way of example, for anembodiment such as that shown in FIG. 1 wherein only split-collectorcontacts C₅, C₅ ', C₇, and C₇ ', are present, the injection suppressionregions between single collector contacts C₃ and C₄ would touch forminga single injection suppression region and the injection suppressionregions between single collector contacts C₁ and C₂ would touch forminga single collector contact.

FIG. 5 illustrates a plan view of an embodiment of a two dimensional(2D) magnetic field sensor 30 in accordance with the present invention.Reference numerals for FIG. 5 corresponding to like elements of FIG. 1have been retained. For clarity, conductive traces 31 and 32 have beenomitted from FIG. 5. Similar to the embodiment of FIG. 1, 2D magneticfield sensor 30 comprises a semiconductor substrate 11 and a base region13 disposed therein. Further, magnetic field sensor 30 has an emitterregion 36 formed within base region 13, wherein emitter region 36 has arectangular shape having four sides and four corners. Emitter region 36is an N⁺ region having, for example, a dopant concentration of 10²⁰atoms/cm³. A second portion of base region 13 is doped with the N typedopant to form an N⁺ collector region 37 that conforms to the shape ofemitter region 36 and laterally surrounds and is spaced apart fromemitter region 36. A substrate contact region 18 of N⁺ type dopant isformed in a portion of semiconductor substrate 11 adjacent to baseregion 13. By way of example, collector region 37 and substrate contactregion 18 have concentrations of 10²⁰ atoms/cm³.

An optional base contact region 39 is formed by doping a portion of baseregion 13 with a P⁺ type dopant. Base contact region 20 is a rectangularshaped region that conforms to the shape of collector region 37, andlaterally surrounds and is spaced apart from collector region 37. Inaddition, four injection suppression regions 41 are formed through eachcorner of emitter region 36 by doping the portions of base region 13 andemitter region 36 with a P⁺ type dopant. Preferably, the concentrationof P⁺ type dopant is 10²⁰ atoms/cm³. As those skilled in the art areaware, metal contacts (not shown) are formed such that an emittercontact, a base contact, collector contacts are formed. Preferably, fourcollector contacts, C₁₃ -C₁₆, are formed on principal surface 12 incollector contact region 37, wherein one collector contact is formed oneach side of emitter region 36 such that the collector contacts arebilaterally symmetric about emitter region 36. It shall be understoodthat 2D magnetic field sensor 30 is a bilaterally symmetric device.

In a forward active mode of operation, a constant current is applied tobase contact region 39, a constant voltage is applied to each collectorcontact C₁₃ -C₁₆, and a constant voltage is applied to substrate contactregion 18. In this mode of operation, electrons are emitted from emitterregion 36 into base region 13 and collected by collector region 37. Inthe absence of a magnetic field, the number of electrons collected bycollector region 37 are evenly distributed among collector contacts C₁₃-C₁₆ because of the symmetry of magnetotransistor 30. When a magneticflux density comprising a B_(x) and a B_(y) component is applied tomagnetotransistor 30, the B_(x) and B_(y) components create an imbalancein the number of electrons collected by the collector contacts due tothe action of the Lorentz force. More particularly, the B_(x) componentdeflects electron flow such that the number of electrons collected bycollector contact C₁₅ increases and the number of electrons collected bycollector contact C₁₃ decreases. The B_(y) component, on the other hand,increases the number of electrons collected by collector contact C₁₆ anddecreases the number of electrons collected by collector contact C₁₄.Thus, a difference in the collector current between collector contactsC₁₃ and C₁₅ is used to detect B_(x), and the difference in the collectorcurrents between collector contacts C₁₄ and C₁₆ is used to detect B_(y).

By now it should be appreciated that the present invention discloses acollector arrangement for a magnetotransistor and method of making saidmagnetotransistor. In the present invention, a collector region isformed such that it is a continuous structure, extending from theprincipal surface into the base region. Further, the collector regionsurrounds and is spaced apart from the emitter region. A plurality ofcollector contacts are formed in the collector region, wherein thecollector contacts are symmetrically distributed around the emitterregion.

In the 3D magnetotransistor embodiment, the collector contacts includesplit-collector contacts (collector contacts C₅ -C₈ and C₅ '-C₈ '),whereas split-collector contacts are absent from the 2D embodiment. Inthe present invention all sources of noise, i.e., emitter, base,collector-base junction, etc. have impacted upon the charge carriers bythe time they reach the collector region. Thus, splitting the chargecarriers between the collector contacts correlates the noise within thecollector region thereby eliminating noise related distortion.

Further, cross sensitivity in the 3D magnetotransistor embodiment iseliminated by placing at least two pairs of split-collector contactsacross from each other on opposite sides of the emitter region such thatthe at least two pairs of split-collector contacts are between the x andy axes. A first of the pair of split-collector contacts on one side ofthe emitter region is electrically coupled to a first of the pair ofsplit-collector contacts on the opposite side of the emitter region, anda second of the pair of split-collector contacts on the one side of theemitter region is electrically coupled to a second of the pair ofsplit-collector contacts on the opposite side of the emitter region.Under the influence of a magnetic flux density, the number of chargecarriers arriving in the vicinity of a collector contact, i.e., thecollector current, is increased in the collector contacts on the oneside of the emitter region and decreased in the collector contacts onthe opposite side of the emitter region. Accordingly, the net change incollector current in the coupled contacts is zero, hence thecross-sensitivity is also zero. In other words, the B_(x) and B_(y)components of the magnetic flux density do not change the total numberof charge carriers collected by the collector region.

I claim:
 1. A method of forming a semiconductor magnetic field sensor,comprising the steps of:providing a semiconductor substrate of a firstconductivity type, the semiconductor substrate having a principalsurface; forming a base region of a second conductivity type in thesemiconductor substrate, the base region extending from the principalsurface into the semiconductor substrate; forming an emitter region ofthe first conductivity type in the base region, the emitter regionextending from the principal surface into the base region; forming acollector region of the first conductivity type in the base region, thecollector region being a continuous structure that is spaced apart fromand laterally surrounds the emitter region; providing an electricalcontact to the base region; providing an electrical contact to theemitter region; and providing a plurality of collector contacts to thecollector region, wherein a current flowing into some of the pluralityof collector contacts is changed by a first component of a magnetic fluxdensity, and the current flowing into others of the plurality ofcollector contacts is changed by a second component of the magnetic fluxdensity.
 2. A method of forming a semiconductor magnetic field sensor asclaimed in claim 1, further comprising the steps of:forming the emitterregion in an octagonal shape, the emitter region having eight sides andeight corners; forming a base contact region, the base contact regionspaced apart from and laterally surrounding the emitter region; forminga plurality of injection suppression regions, the plurality of injectionsuppression regions extending into the emitter region to form aplurality of conduction channels through which charge carriers flow; andproviding at least one collector contact in the collector regionadjacent each side of the emitter region, wherein a current flowing intoat least two of the collector contacts is changed by a third componentof the magnetic flux density.
 3. A method of forming a semiconductormagnetic field sensor as claimed in claim 1, further comprising thesteps of:providing a substrate contact region in the semiconductorsubstrate region of the first conductivity type; and providing asubstrate contact to the substrate contact region.
 4. A method offorming a semiconductor magnetic field sensor as claimed in claim 1,further comprising the steps of:forming the emitter region in a circularshape; forming a base contact region, the base contact region spacedapart from and laterally surrounding the emitter region; forming aninjection suppression region, the injection suppression region extendinginto the emitter region to form a plurality of conduction channelsthrough which charge carriers flow; and providing at least eightcollector contacts in the collector region adjacent the emitter region,wherein a first collector contact is positioned 90 degrees from a secondcollector contact and a fourth collector contact, and the firstcollector contact is positioned 180 degrees from a third collectorcontact, and a first pair of split-collector contacts is positioned 180degrees from a second pair of split-collector contacts and the currentflowing into the first and the third collector contacts is changed bythe first directional component of the magnetic flux density, thecurrent flowing into the second and the fourth collector contacts ischanged by the second directional component of the magnetic fluxdensity, and a current flowing into the first and second pairs ofsplit-collector contacts is changed by a third directional component ofthe magnetic flux density.
 5. A method of forming a semiconductormagnetic field sensor as claimed in claim 4, wherein the step ofproviding at least eight collector contacts in the collector regionadjacent the emitter region includes coupling a first split-collectorcontact of the first pair of split-collector contacts with a firstsplit-collector contact of the second pair of split-collector contactsand coupling a second split-collector contact of the first pair ofsplit-collector contacts with a second split-collector contact of thesecond pair of split-collector contacts.
 6. A method for sensing adirectional component of a magnetic flux density, comprising the stepsof:providing a transistor having an emitter region of a firstconductivity type, a base region of a second conductivity type, and acontinuous collector region of the first conductivity type, wherein theemitter and the collector regions are formed within the base region andthe collector region surrounds and is spaced apart from the emitterregion; forming a plurality of collector contacts which contact thecollector region, wherein a first and a second of the plurality ofcollector contacts are adjacent opposite sides of the emitter region anda third and a fourth of the plurality of collector contacts are adjacentopposite sides of the emitter region; applying a magnetic field to thetransistor; injecting charge carriers from the emitter region throughthe base region; and collecting the charge carriers in the collectorregion, including collecting a first portion of the charge carriers viathe first collector contact, collecting a second portion of the chargecarriers via the second collector contact, collecting a third portion ofthe charge carriers via the third collector contact, and collecting afourth portion of the charge carriers via the fourth collector contact,the first and second portions having a different number of chargecarriers in the presence of a first directional component of a magneticflux density and the third and fourth portions having a different numberof charge carriers in the presence of a second directional component ofthe magnetic flux density.
 7. The method of claim 6, wherein the step ofproviding a transistor further comprises forming a plurality ofinjection suppression regions which extend into portions of the emitterregion.
 8. The method of claim 7, wherein the step of providing atransistor includes forming circular shaped emitter and collectorregions.
 9. The method of claim 7, wherein the step of forming aplurality of injection suppression regions includes doping the portionsof the emitter region with an impurity material of the secondconductivity type.
 10. The method of claim 9, wherein the step ofproviding a transistor includes forming rectangular shaped emitter andcollector regions, the emitter region having a plurality of corners, andwherein the step of forming a plurality of injection suppression regionsincludes forming one of the plurality of injection suppression regionsin each of the plurality of corners.
 11. The method of claim 6, whereinthe step of providing a transistor includes forming octagonal shapedemitter and collector regions having first and second split-collectorcontacts adjacent a first side of the emitter region and third andfourth split-collector contacts adjacent a second side of the emitterregion, and the step of collecting the charge carriers in the collectorregion includes collecting first and second subportions of a fifthportion of the charge carriers via the first and third split-collectorcontacts, respectively, collecting first and second subportions of asixth portion of the charge carriers via the second and fourthsplit-collector contacts, respectively, the fifth and sixth portionshaving a different number of charge carriers in the presence of a thirddirectional component of the magnetic flux density.
 12. The method ofclaim 11, wherein the step of providing a transistor includes formingfifth and sixth split-collector contacts adjacent a third side of theemitter region and forming seventh and eighth split-collector contactsadjacent a fourth side of the emitter region, and the step of collectingthe charge carriers further includes collecting third and fourthsubportions of the fifth portion of the charge carriers via the fifthand seventh split-collector contacts, respectively, and the step ofcollecting the charge carriers further includes collecting third andfourth subportions of the sixth portion of the charge carriers via thesixth and eighth split-collector contacts, respectively.
 13. The methodof claim 11, wherein the step of providing a transistor includeselectrically coupling the first, third, fifth, and seventhsplit-collector contacts and electrically coupling the second, fourth,sixth, and eighth split-collector contacts.
 14. A method for sensing adirectional component of a magnetic flux density, comprising the stepsof:providing a semiconductor substrate comprising a base region of afirst conductivity type, the base region having a base contact regionand containing a continuous collector region of a second conductivitytype, the continuous collector region surrounding and spaced apart froman emitter region of the second conductivity type; forming a pluralityof collector contacts in contact with the continuous collector region;forming at least one conduction channel for transporting charge carriersto at least one of the plurality of collector contacts; and injectingcharge carriers from the emitter region, through the at least oneconduction region, to the continuous collector region, a first portionof the charge carriers collected at a first collector contact of theplurality of collector contacts, a second portion of the charge carrierscollected at a second collector contact of the plurality of collectorcontacts, a third portion of the charge carriers collected at a thirdcollector contact of the plurality of collector contacts, and a fourthportion of the charge carriers collected at a fourth collector contactof the plurality of collector contacts, the first and second portionsbeing of different amounts in the presence of a first directionalcomponent of a magnetic flux density, and the third and fourth portionsbeing of different amounts in the presence of a second directionalcomponent of the magnetic flux density.
 15. The method of claim 14,wherein the step of injecting charge carriers from the emitter region,through the at least one conduction region, to the continuous collectorregion further comprises applying constant current to the base contactregion, applying a constant voltage to the plurality of collectorcontacts in the collector region, and applying a constant voltage to asubstrate contact region.
 16. The method of claim 14, wherein the stepof forming a plurality of collector contacts in contact with thecollector region includes forming the plurality of collector contactssymmetrically distributed on the continuous collector region.
 17. Themethod of claim 16, wherein the step of forming at least one conductionchannel includes forming four conduction channels, a first conductionchannel for transporting charge carriers to the first collector contact,a second conduction channel for transporting charge carriers to thesecond collector contact, a third conduction channel for transportingcharge carriers to the third collector contact, and a fourth conductionchannel for transporting charge carriers to the fourth collectorcontact.
 18. The method of claim 14, wherein the step of injectingcharge carriers further includes collecting a first subportion of afifth portion of the charge carriers at a first split-collector contactof a first set of split-collector contacts, collecting a secondsubportion of the fifth portion of the charge carriers at a firstsplit-collector contact of a second set of split-collector contacts,collecting a first subportion of a sixth portion of the charge carriersat a second split-collector contact of the first set of split-collectorcontacts, and collecting a second subportion of the sixth portion of thecharge carriers at a second split-collector contact of the second set ofsplit-collector contacts, the fifth and sixth portions being ofdifferent amounts in the presence of a third directional component ofthe magnetic flux density.
 19. The method of claim 18 wherein the stepof forming a plurality of collector contacts in-contact with thecollector region includes forming four collector contacts symmetricallydistributed on the continuous collector region and further includesforming third and fourth sets of split-collector contacts, the first,second, third, and fourth sets of split-collector contacts symmetricallydistributed on the continuous collector region.
 20. The method of claim19, wherein the step of forming at least one conduction channel includesforming eight conduction channels, a first conduction channel fortransporting charge carriers to the first collector contact, a secondconduction channel for transporting charge carriers to the secondcollector contact, a third conduction channel for transporting chargecarriers to the third collector contact, a fourth conduction channel fortransporting charge carriers to the fourth collector contact, a fifthconductive channel for transporting charge carriers to ,the first set ofsplit-collector contacts, a sixth conductive channel for transportingcharge carriers to the second set of split-collector contacts, a seventhconductive channel for transporting charge carriers to the third set ofsplit-collector contacts, and an eighth conductive channel fortransporting charge carriers to the fourth set of split-collectorcontacts.